MIPS: Optimise Math.floor(x/y) to use integer division for MIPS.

Use div instruction if some divisors do not have magic number.

Based on commit r11427 (318a9598).

This commit also ports commit r15161 (554d45c1).

BUG=

Review URL: https://codereview.chromium.org/16951016
Patch from Dusan Milosavljevic <Dusan.Milosavljevic@rt-rk.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15181 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Add Gergely Kis to MIPS owners file.

BUG=
R=danno@chromium.org

Review URL: https://codereview.chromium.org/17175003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15182 ce2b1a6d-e550-0410-aec6-3dcde31c8c00